Although many well known examples of soil-removal shovels exist in the prior art, construction workers and homeowners typically use what is typically referred to as a “contractor's shovel”. The typical contractor's shovel is readily obtainable in any hardware retail establishment, and consists of a curved metal blade with a sharp point. By providing a concave side to the blade, the soil-carrying ability of the blade is improved over shovels with flat blades. Soil is less likely to fall off of the curved blade than a flat blade. The lower or ground-contacting portion of the blade includes a sharp point that is intended to provide a single point to improve entry of the blade into the soil. The edge of the blade is typically of a thickness equal to the thickness of the remainder of the blade.
Although the typical contractor's shovel described above provides an adequate means of penetrating soil that is soft or sandy, it is inadequate for penetrating hard or packed soils or even moderately hard soils that are covered by grass or other ground coverings. In these situations, as an operator places the point of the shovel against a hard soil surface, places one foot against a foot-engagement surface opposite the cutting edge, and applies force against the foot-engagement surface, the shovel, by virtue of the sharp point, tends to roll from side to side as the point resists penetration into the hard soil. By applying additional force to overcome the resistance of the hard soil, the operator risks ankle, knee, or other leg or back injuries from the large sideways torque caused by the point, the curved sides of the blade, and the excessive force required to break the soil surface.
Leg or back injuries may also occur when using the standard contractor's shovel in any soil, if, for example, the cutting edge of the shovel contacts a root or similar subsurface object. By virtue of the pointed blade and curved sides adjacent the point, a root most likely will be contacted off-center or away from the point. Root contact on the curved cutting edge tends to throw the shovel sideways, in a direction opposite the curved edge contacting the root. The suddenness of impact of the unexpected object with the blade can cause a sudden sideways jerk that can cause injury to the operator's ankle, knee, hip, back, or other areas of the body.
There are several examples in the prior art for improving the stability and root-cutting ability of shovels. These include U.S. Pat. No. 5,533,578 to Powell and U.S. Pat. No. 6,338,511 to Douglas, et al.
U.S. Pat. No. 5,533,578 (hereinafter the '578 patent) describes a two-pointed shovel that includes a bifircated cutting edge consisting of a pair of prongs. The prongs form an indentation of shallow depth with a cutting edge lining the indentation. The indentation and cutting edge are provided to straddle a subsurface root and cut it.
Although the shovel of the '578 patent provides an indentation for cutting roots, it still is less than optimal for minimizing sideways torque. For the indentation to properly cut a root, the root must be of the proper size to fit the indentation and the indentation must center on the root. Unfortunately, not all roots are of the same size, and therefore some roots may be oversized and not fit within the indentation. The oversized root may then become jammed between the pair of prongs, trapping the shovel in the ground and making it hard to extract. Since the indentation area of the blade is a relatively small part of the front edge of the blade, roots may just as easily contact the curved sides of the blade as the indented part, thereby rendering the indentation useless. Additionally, the shovel of the '578 patent, although bifurcated into two prongs, still includes two pointed prongs and sharply curved sides, therefore causing an undesirable strong sideways force on the handle when placed against hard soil with force applied thereto.
U.S. Pat. No. 6,338,511 (hereinafter the '511 patent) describes a shovel including an elongated root-cutting blade including a sharpened root-cutting edge located substantially along the longitudinal centerline of the blade and a pair of side blades projecting from the sides of the blade. Forward facing cutting edges are included on the forward ends of the side blades. The shovel of the '511 patent, although providing three extra root cutting surfaces, is not ideal for penetrating hard soils as a result of the increased friction provided by the extra shovel surface area. The three root cutting surfaces add a significant amount of drag or resistance to the shovel. The additional metal needed to create the three additional root-cutting surfaces would also add significantly to the production cost of the shovel. Although providing three additional root-cutting surfaces, there is no guarantee that roots will be encountered in the proper orientation to contact these surfaces. The shovel of the '511 patent may, in fact, encounter a root perpendicular to and centered on the lower blade of the shovel. In this situation, the lower blade would begin to cut the root and as it progressed through the root the elongated center root-cutting blade would push longitudinally into the root, thereby forcing two cutting blades into the root at once and dramatically increasing resistance to forward advance of the blade.
Accordingly, an improved shovel is needed to provide better stability, improved root cutting ability, and enhanced soil penetrating ability without adding significantly to the overall shovel surface area and thereby increasing resistance with the soil.